After reading Benford’s Law and email subjects at Yiorgos’ blog I was curious if the law stands for email sizes as well. So I did the experiment, for a week of email traffic at a certain mail server, and here is … Continue reading →
Είσαι στο χωράφι και μαζεύεις ελιές.. Ξαφνικά, αρχίζει βροχή από SMS alerts για services που πέφτουν .. Ανοίγεις το netbook και έχεις δίπλα την κεραία με το σήμα 3G στο full.. Priceless! Filed under: System Administration Tagged: 3g, olives, priceless
In preparation for World IPv6 Day on 8 June 2011, I thought I’d check my connectivity.. I visited a test-ipv6 page .. but the page took too long to open, had broken images, timeouts and readiness score 1/10 ! So … Continue reading →
Marios asked me to elaborate a little on the Red Hat Certification Exams and my preparation. I found the lab based exams much better than other multiple choice exams. It doesn’t matter if you do something using the command line, … Continue reading →
Your allocation: 2001:db8/32 You LAN: 2001:db8:2:2001/64 Your device: 2001:db8:2:2001::11 (mydevice.local) Let “host” do the dirty work for you! sotiris@jumbo:~$ host 2001:db8:2:2001::11 Host 1.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.2.2.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa not found: 3(NXDOMAIN) The zone for your /32 is 8.b.d.0.1.0.0.2.ip6.arpa $TTL 1d @ IN SOA ( 42 … Continue reading →
Με τον καινούριο Κανονισμό Διαχείρισης και Εκχώρησης Ονομάτων Χώρου (Domain Names) με κατάληξη .GR (pdf link), που δημοσιεύτηκε από την ΕΕΤΤ στις 14/04/2011, γίνεται υποχρεωτικό πλέον αυτό που είχα γράψει πριν δύο χρόνια στο Resolvers Vs. Authoritative DNS Αρθρο 17, … Continue reading →
Personally, I don’t block spam. I keep receiving it because I find it interesting to study. Where does it come from? Single IP? Single domain? Botnet? Who does it target? list of harvested emails or specifically targeted? Is it sent … Continue reading →
All modern hard disks are S.M.A.R.T. enabled. “SMART is a monitoring system for hard disks to detect and report on various indicators of reliability, in the hope of anticipating failures”. Most people never pay attention to the numbers, some people … Continue reading →
sotiris@banana:~$ ping 95.38.104.232 PING 95.38.104.232 (95.38.104.232) 56(84) bytes of data. From 95.38.104.225 icmp_seq=1 Time to live exceeded From 95.38.104.225 icmp_seq=2 Time to live exceeded This was the first time I saw an internet host more than 30 hops away.. It … Continue reading →
My IPv6 Certified SAGE t-shirt from Hurricane Electric has arrived, and it’s full of coolness! Even cooler from he.net, since I’m a Certified IPv6 SAGE, my organization now qualifies for lower pricing on IP transit from their tier1 ipv6 network! … Continue reading →
I inherited an old web interface, that used default values in form input fields as follows: <INPUT type="text" name="username" value="Please input a username"> I have now changed it to the following <INPUT type="text" name="username" value="username.ath.forthnet.gr" onblur="if(this.value=='') this.value=this.defaultValue;" onfocus="if(this.value==this.defaultValue) this.value='';"> Time … Continue reading →
Write a regular expression to match a MAC address. Go. Take 1: ([0-9a-f]{2}:){5}[0-9a-f]{2} Matches: 00:19:db:d0:8e:3c Take 2: ([0-9a-fA-F]{1,2}[:-]){5}[0-9a-fA-F]{1,2} Matches: 00-c-DB-a0-8E-f Filed under: System Administration Tagged: mac address, regexp
A friend recently told me of a small problem he was asked to resolve: “Find all duplicate UIDs in your /etc/passwd file. Print them along with the associated usernames. You may use shell, perl or python”. My first, almost instant, … Continue reading →
Ρώτησε σ’ενα tweet ο @pgaval: Νεφοπληροφορική ο προτεινόμενος από τον @sterzidi όρος για το cloud computing. Να τον κρατήσουμε; και ο @hakmem απάντησε: ΓΙΑΤΙ πρέπει να μεταφράζουμε κάθε όρο; Ποτέ δεν είμουν υπέρ της μετάφρασης των πάντων στα Ελληνικά. Οσοι είναι υπερ, παρακαλώ να σταματήσουν να διαβάζουν το περιοδικό RAM και να διαβάζουν το ΜΤΠ. [...]
Given a (forward) zone file, here is a quick way to automagically generate all the reverse zone files you need: #!/usr/bin/perl # # does not generate PTR records for $GENERATE lines # does not generate PTR records for CNAME and AAAA RRs # generates PTR records for A RRs # %revzones = (); $domain = [...]
I really don’t like the underscore [ _ ] character! Please don’t use it in your hostnames, although it appears to work, it’s actually not valid and generates warnings and errors. Please don’t use it in your filenames, filesystems can handle files/dirs with whitespace these days. Please don’t ask ‘underscore or dash?’ when I say [...]
Δυο χρόνια είχα να σε δω, και σε συνάντησα ξανά σ’ ενα ISP. Περνούσες patches, service packs σ’ ένα θηρίο και τα καλά σου φόραγες, σαν να’ σουν πωλητής. Δεν ήσουνα programmer, για να πω “καλά να πάθεις”, μα ούτε web developer, για να πω “βάλε μυαλό”. Solaris κι HP admin 2 χρόνια κι 6 [...]
The good people over at Hurricane Electric have setup an IPv6 Certification Project. It allows you to certify your ability to configure IPv6, and to validate your IPv6 servers configuration. Through the certification process set you will be able to: Prove that you have IPv6 connectivity Prove that you have a working IPv6 web server [...]
Πρόσφατα οι περισσότεροι Ελληνικοί ISPs απάντησαν σε ερωτηματολόγιο σχετικά με το IPv6 που τους έστειλε το adslgr.com. Κάποιοι αναφέρουν στα πλεονεκτήματα τον τεράστιο αριθμό διευθύνσεων που προσφέρει το IPv6. Σε διαφορετικό site, ο cheaplog σχολιάζει σε ένα post του elawyer: Μια ιδέα είναι να υποχρεωθούν τουλάχιστο οι Έλληνες ISPs να παρέχουν στατικές IPs μετά το [...]
ipv6calc is a swiss-army knife utility to manipulate ipv6 addresses. It can be used to convert IPv6 addresses from one format to another and extract embedded information. $ ipv6calc -q --out revnibbles.arpa 2002:d4fb:e54::1 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.4.5.e.0.b.f.4.d.2.0.0.2.ip6.arpa. (the above can also be obtained easily using dig -x 2002:d4fb:e54::1) $ ipv6calc -q --action conv6to4 --in ipv4 193.92.110.1 --out ipv6 [...]